An ion-etching technique has been successfully applied to the production of blazed holographic plane gratings having various blaze angles ranging from 7 to 26 degrees. Efficiencies of the gratings thus produced were measured in the Littrow configuration as functions of an ion-etching condition, wavelength, and angle of incidence. The maximum efficiency for p -polarized light was found to be more than 64 per cent at about 3250 + for gratings etched at the beam angle of 80 degrees. Experimental results show that ion-etched gratings have the blaze property equivalent to that of holographic gratings made by means of Sheridon's method.